Two-Stage Chemical Absorption–Biological Reduction System for NO Removal: System Start-up and Optimal Operation Mode

Abstract

A novel chemical absorption–biological reduction (CABR) integrated process, employing Fe(II)EDTA as an enhanced absorbent, is a promising technology for nitrogen oxides removal. In this work, we developed a new two-stage CABR system applying a mixed cultivation model of denitrifying bacteria and iron-reducing bacteria, which consists of a sieve-plate tower and a bioreduction tower to separate the absorption and reduction processes. The start-up period of the two-stage system was shortened to 19 days, while that of the one-stage CABR system was 46 days. In addition, the two-stage CABR system featured a better oxygen-resistance ability and a higher NO removal loading. In effort to optimize system operation, we compared different modes of system operation and found that (1) continuous addition of glucose was better than the batch-type addition and that (2) the NO removal efficiency could be maintained at >90% while the FeEDTA concentration was higher than 4 mmol/L; however, reducing the initial concentration...